Means for conveying electrically charged photocopy paper

ABSTRACT

THE PRESENT INVENTION RELATES TO A FIXEDLY MOUNTED SUPPORTING ELEMENT SERVING AS A COUNTERLECTRODE OF THE CHARGING DEVICE, AND HAVING A DISCONTINUOUS SURFACE IN CONTACT WITH THE ELECTROSTATICALLY CHARGED PHOTOCOPY PAPER. THE DISCONTINUOUS SURFACE REDUCES THE TENDENCY OF THE CHARGED PAPER TO ADHERE TO THE COUNTER-ELECTRODE, AND TO ENSURE SMOOTH CONVEYANCE OF THE COPYING PAPER.

Jan. 5, 1971 H. KLEINSTRA ETAL 3,552,847

MEANS FOR CONVEYING ELECTRICALLY CHARGED PHOTOCOPY IAIUH Filed Feb. 6. 1968 United States Patent US. Cl. 355-3 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a fixedly mounted supporting element serving as a counterelectrode of the charging device, and having a discontinuous surface in contact with the electrostatically charged photocopy paper. The discontinuous surface reduces the tendency of the charged paper to adhere to the counter-electrode, and to ensure smooth conveyance of the copying paper.

BACKGROUND OF THE INVENTION The present invention relates to an electro-photographic photocopy machine, in which the copying paper, which is provided with a light-sensitive semiconductive layer, is successively conveyed along an electrostatic charging device, comprising a highly energized live wire and a counterelectrode supporting the paper, and along an illumination device.

In using such machines, problems are encountered in conveying the charged copying paper when passing the charging device and the illumination device. As a result of the electrostatic charge the paper shows a strong tendency to attach itself to the surfaces with which it comes into contact. It is for this reason that for the conveyance of the copying paper along this part of its way through the photocopy machine no fixedly mounted supporting elements are used, but co-moving supports, such as rollers and belts are employed. Such moving supports require care to be driven at the proper velocity, whilst in addition to this measure precautions are necessary to prevent the paper from being wound around any of the rollers or belts.

It is the object of the invention to secure a smooth conveyance of the copying paper with the aid of simple, non-moving means, so that the photocopy machine can be more compact, more reliable and less expensive than the known machines.

SUMMARY OF THE INVENTION For this purpose, the photocopy machine according to this invention employs a counterelectrode of the charging device constructed as a fixedly mounted supporting element, having a discontinuous surface supporting the copy paper along the charging device and the illumination device.

Owing to the interruptions in the supporting surface, only a part of the surface of the electrostatically charged copying paper is in touch with the supporting element and the adhesive tendency of the paper is decreased to such a degree, that it causes no trouble when it glides along the supporting element. On the other hand, what little adhesive tendency is left will keep the paper in contact with the supporting element while passing the illumination device, so that an incorrect position of the paper and the faults in the copy resulting therefrom are prevented. Since undesirable adhesion has been decreased,

the supporting element can be made longer eliminating the need for added conveying or guiding means.

According to a further object of the invention, the discontinuous surface is formed by a number of ribs of the supporting element. In a preferred embodiment of the invention said ribs are disposed under a small angle with the conveying direction of the copying paper, in such a way as to diverge symmetrically with respect to this conveying direction. This has the result that the paper is smoothed in transverse direction and it forms an extra precaution against the paper being in an incorrect position during exposure.

In a simple embodiment of cheap construction the ribs consist of wires provided on the supporting element.

In another embodiment, the discontinuous plate is formed by a suitably etched plate, or other means for providing a grooved surface.

DRAWINGS The invention is further elucidated hereinafter with reference to the accompanying drawing, in which FIG. 1 shows a cross-section of an embodiment of a photocopying machine according to the invention, and

FIG. 2 shows a front view of the supporting element.

DESCRIPTION In the front wall 1 of a substantially light-proof box, there are provided two feeding slots between the horizontal plates 2, 3 and 4. A sheet of copying paper consisting of an insulating carrier and a light-sensitive semiconductive layer provided thereon, is shoved between the plates 3 and 4 with its sensitive layer turned upwards. Simultaneously, the original is shoved between the plates 2 and 3 with the side which is to be copied turned downwards.

The original is then passed between the rollers 5 and 6 by the plate 3, the rollers 5 and 6 further conveying the said original upwards along the supporting plate 7 to the rollers 8 and 9. These rollers *8 and 9 take the original through the opening 10 outside the box, where it remains lying on the box.

The copying paper is fed by the plate .3 between the rollers 11 and 12, which convey it downwards along the supporting plate 13 to the rollers 14 and 15. On its way it passes an electrostatic charging device, comprising a wire-shaped electrode 16, which is kept at a negative voltage of, e.g. 6000 v., a screen 17 having an equivalent positive voltage and the supporting plate 13, which functions as a counterelectrode and has the same voltage as the screen 17. In this way, the light-sensitive layer of the copying paper gets a negative charge, and the back side thereof gets a positive charge.

The rollers 5, 6, 8, 9, 11, 12, 14 and 15 are rotated by a common driving gear, the peripheral velocities of all the aforesaid rollers being equal, so that the original and the copying paper move upwards or downwards at the same velocity.

The supporting plate 13, along which the copying paper is guided during the charging and the exposure, is a metal plate, onto which metal wires 32 are wound, preferably in a symmetrical way, as shown in FIG. 2. Owing to this, the copy paper is not in contact with the plate 13 itself, but only with the wires 32 and in this way it meets with very little friction in spite of the electrostatic charge and can be conveyed to the rollers 14 and 15 by the rollers 11 and 12 without further conveying means.

Owing to their symmetrical divergent position, the wires 32 exert some transverse force on the copying paper and during the charging and exposure the paper is also kept desirably smooth in transverse direction.

When passing the supporting plate 7, the original is illuminated by the lamp 18 which is provided with a refiector. By means of an optical systemcor'nprising'one or more lenses 19 and a. mirror 20 and being mounted against the back wall of the box, an image of the moving original is projected onto the copying paper which is moving along the supporting plate 13 at the same speed.

At the location where the copying paper is exposed, the

sensitive layer becomes conductive and the static charge disappears.

Only in the places corresponding to the dark parts of the original, the charge remains present, so that on the copying paper there has been formed an electrostatic image of the original.

After the exposure, the rollers 14 and 15 convey the copying'paper into the developing device 21. This consists of a tank 22 containing developing liquid, as also of a guiding device 23 and a pressing roller 24, with the aid of which the copying paper is conveyed through the developing liquid. 1

In the developing liquid there are solid particles, which are attracted by the electrostatic charge which is still present on the copying paper and which there attach themselves to the surface of the coying paper, so that an image of the original is formed on the copying paper.

The copy thus formed is conveyed out of the developingapparatus by the rollers 25 and 26 and is exposed to the air stream produced by the blower 27. By this 'air stream, the evaporation of the liquid still adhering to the copying paper is promoted. At the same time, the air stream gives the copy a downward bend, so that it lays itself with its back side against the cylindrically bent part of the perforated plate 28 and moves along said plate towards its flat, horizontal part, which extends as far as over the delivery slot 29 is the front wall 1. The air stream, which is guided through the bottom 30 of the box in the direction of the delivery slot 29, keeps the copy with its back side against the plate 28, so that the sensitive side of the copy, while drying, remains untouched and cannot be injured.

The present invention can be employed with a drydeveloping system, and various systems other than that pi ts in ad s fs initiat n slsst statiq shares to the photocopy paper. While it is preferable to employ a regular pattern of ribs on the supporting surface, irregular patterns can also be used. The discontinuous surface can be formed by other techniques such as an etched'p1ate,'although the use of wires 'is preferred. Various other modifications will of course suggest themselves to those skilled in the art.

Having described the present invention, that which is sought to be protected is set forth in the following claims. i

1. In an electrostatic. photocopy machine wherein copying paper which is provided with alight-sensitive semiconductive layer is conveyed along and electrostatic charging device, comprising a highly energized live wire and a counterelectrode supporting the paper, the improvement wherein the counterelectrode of the charging device is constructed as a fixedly mounted stationary supporting element having a discontinuous supporting surface for supporting the copy paper along the charging device.

2. The improvement of claim 1, wherein the discontinuous supporting surface is formed by ribs disposed approximately in the conveying direction of the copying paper. 1

3. The improvement of claim 2, wherein the ribs of conveying direction for the copying paper.

4. The improvement of claim 2 wherein the ribs are formed by wires provided on the supporting element.

5. The improvement of claim 1 wherein said copying paper is conveyed successively along the charging device as well as an illumination device while supported by said counterelectrode having a discontinuous supporting surface.

References Cited UNITED STATES PATENTS 1,106,504 8/1914 Floeter 355-108 11/1960 Francis 355-12" 

